Studies on the sequence circuits of harmonics in three-phase power system

A fresh idea is proposed in this paper that a system, with loads of nonlinear voltage-current characteristics, can not be a balanced circuit. Theoretical analysis and simulations are given. One important conclusion is reached: in the analysis of harmonics of each order, three symmetric three phase circuits, rather than only one-phase circuit should be used. An analytical method of the sequence circuits of harmonics in three-phase power systems is also presented.